Stephanie Louise Kwolek (July 31, 1923 – June 18, 2014) was an American chemist who invented poly-paraphenylene terephthalamide—better known as Kevlar. She was born in the Pittsburgh suburb of New Kensington, Pennsylvania. Kwolek won numerous awards for her work in polymer chemistry.

Early life and education

Kwolek was born to Polish immigrant parents in New Kensington, Pennsylvania in 1923. Her father, John Kwolek (Polish: Jan Chwałek), died when she was ten years old.

He was a naturalist by avocation, and Kwolek spent hours with him, as a child, exploring the natural world. She attributed her interest in science to him and an interest in fashion to her mother, Nellie (née Zajdel) Kwolek. In 1946, Kwolek earned a degree in chemistry from Margaret Morrison Carnegie College of Carnegie Mellon University. She had planned on becoming a doctor and hoped that she could earn enough money from a temporary job in a chemistry-related field to go to medical school.

DuPont career

In 1946, Hale Charch, a future mentor to Kwolek, offered her a position at DuPont's Buffalo, New York facility because after telling Kwolek he would get back in touch within two weeks, Stephanie asked Charch if he could make a decision faster because she had to answer another job offer. Charch called in his secretary and drafted an offer letter on the spot.

Although Kwolek initially only intended to work for DuPont temporarily, she found the work interesting enough to stay and not pursue a medical career. She moved to Wilmington, Delaware in 1950 to continue to work for DuPont. In 1959, she won a publication award from the American Chemical Society (ACS).

Kevlar

While working for DuPont, Kwolek invented Kevlar. In 1964, in anticipation of a gasoline shortage, her group began searching for a lightweight yet strong fiber to be used in tires. The polymers she had been working with at the time, poly-p-phenylene terephthalate and polybenzamide, formed liquid crystal while in solution that at the time had to be melt-spun at over 200 degrees Celsius, which produced weaker and less stiff fibers. A unique technique in her new projects and the melt condensation polymerization process was to reduce those temperatures to between 0-40 degrees Celsius.

The solution was "cloudy, opalescent upon being stirred, and of low viscosity" and usually was thrown away. However, Kwolek persuaded technician Charles Smullen, who ran the spinneret, to test her solution. She was amazed to find that the new fiber would not break when nylon typically would. Not only was it stronger than nylon, Kevlar was ounce for ounce five times stronger than steel. Both her supervisor and the laboratory director understood the significance of her discovery, and a new field of polymer chemistry quickly arose. By 1971, modern Kevlar was introduced. However, Kwolek was not very involved in developing practical applications of Kevlar.

Retirement

In 1986, Kwolek retired as a research associate for DuPont. Toward the end of her life, she consulted for DuPont, and also served on both the National Research Council and the National Academy of Sciences. During her 40 years as a research scientist, she filed and received either 17 or 28 patents. In 1995, she became the fourth woman to be added to the National Inventors Hall of Fame.

In 1996, she received the National Medal of Technology; and, in 2003, she was added to the National Women's Hall of Fame. She received the 1997 Perkin Medal from the American Chemical Society, and a 1980 award from the ACS for "Creative Invention".

Kwolek died at the age of 90 on June 18, 2014.